School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore.
NTU Institute of Structural Biology, Nanyang Technological University, Singapore 636921, Singapore.
Sci Adv. 2024 Sep 20;10(38):eado8107. doi: 10.1126/sciadv.ado8107.
Polyamines, characterized by their polycationic nature, are ubiquitously present in all organisms and play numerous cellular functions. Among polyamines, spermidine stands out as the predominant type in both prokaryotic and eukaryotic cells. The PotD-PotABC protein complex in , belonging to the adenosine triphosphate-binding cassette transporter family, is a spermidine-preferential uptake system. Here, we report structural details of the polyamine uptake system PotD-PotABC in various states. Our analyses reveal distinct "inward-facing" and "outward-facing" conformations of the PotD-PotABC transporter, as well as conformational changes in the "gating" residues (F222, Y223, D226, and K241 in PotB; Y219 and K223 in PotC) controlling spermidine uptake. Therefore, our structural analysis provides insights into how the PotD-PotABC importer recognizes the substrate-binding protein PotD and elucidates molecular insights into the spermidine uptake mechanism of bacteria.
多胺具有多阳离子特性，普遍存在于所有生物中，发挥着多种细胞功能。在多胺中，亚精胺是原核和真核细胞中主要的类型。属于三磷酸腺苷结合盒转运蛋白家族的 中的 PotD-PotABC 蛋白复合物是一种亚精胺优先摄取系统。在这里，我们报告了多胺摄取系统 PotD-PotABC 在各种状态下的结构细节。我们的分析揭示了 PotD-PotABC 转运蛋白的独特“内向”和“外向”构象，以及“门控”残基（PotB 中的 F222、Y223、D226 和 K241；PotC 中的 Y219 和 K223）的构象变化，这些残基控制着亚精胺的摄取。因此，我们的结构分析提供了有关 PotD-PotABC 进口器如何识别底物结合蛋白 PotD 的见解，并阐明了细菌中亚精胺摄取机制的分子见解。
